The present invention relates to a control apparatus and method for the powertrain of a vehicle having an engine or an electric motor and an automatic transmission, and a driving shaft.
Generally, in order to control precisely the powertrain of a vehicle, it is desirable to control it by using the driving shaft torque. In the prior art, because it is difficult to detect directly the driving shaft torque, the control of an automatic transmission is performed briefly by detecting the opening of a throttle valve for adjusting the amount of air taken into the engine of the vehicle, and the vehicle speed.
Recently, there is known a technique in which the driving shaft torque is calculated and estimated based on the characteristics of a torque converter using the speed ratio of the engine speed to the turbine speed as the parameters.
Because the control value is obtained from the opening of the throttle valve and the vehicle velocity, there is a problem that it is difficult to control precisely the transmission as compared with the method using the driving shaft torque. Further, In another method in which the driving shaft torque is calculated and estimated by using the characteristics of the torque converter, the driving shaft torque is calculated and estimated on the basis of the data table of the torque converter characteristics obtained by the experiments when the vehicle was developed. Therefore, even if the fluid in the torque converter deteriorates with age, the change in the torque converter characteristics may not be considered in the above method. As a result, the difference occurs between the calculated and estimated value of the driving shaft torque after the change with age and the actual value of the driving shaft torque. Accordingly, it is difficult to control precisely the transmission.